The employment of NVM in high-volume system-on-chips (SoCs) for televisions, computers, and mobile devices has become increasingly popular. NVM is used to store a wide range of information, such as encryption keys, trimming values, configuration settings, memory patching, and firmware (e.g., test code, boot code, and application code).
One-time programmable (OTP) NVM has been employed in many applications. Conventional OTP NVM cells can use a floating gate as a storage medium and can be programmed only one time. Thus, no device update is possible.
Yet, there are many high-value applications that require the device to be updated, such as firmware updates for mobile devices, televisions, and other electronic devices. Thus, there are many applications that require MTP NVM. However, existing MTP solutions include dual poly-gate NVM or charge-trapping type poly-silicon-oxide-silicon nitride-oxide-silicon (SONOS) NVM, which require additional masking steps and process complexity, which in turn increases cost.
A need therefore exists for a methodology enabling fabrication of a low-cost MTP NVM utilizing a minimum of masks, and the resulting device.